Research is directed toward (1) sequencing spacer regions from 5S DNA of various eucaryotes, (2) studying how lambda CI repressor interacts with lambda major rightward and leftward promoters, and (3) studying how lac repressor interacts with lac operator DNA. Part 1) is being done by primer repair synthesis using chemically synthesized primers annealed to 5S DNA. Parts 2) and 3) are being investigated by first chemical synthesis of the control DNA and then studying by various chemical, biochemical, and physical chemical techniques how the appropriate repressor interacts with control DNA.